Heat-transferring apparatus



2 Sheets-Sheet F. H. BRAMWELL Filed July 23 Vim@ April 9, 1929.

April 9, 1929. F. H. BRAMWELL HEAT TRANSFERRING APPARATUS Filed July 23,1926 2 Sheets-Sheet Patented Am. ltlll.

rnAncIs HERBERT BRAMWnLL, onnUNvEG'AN, HAnTroRD, ENGLAND, AssIeNon ToTION OF NEV YORK.

ne YORK, A oon-romi- HEAT-TRANSFERR'ING APPARATUS.

Application filed'Juiy 23, 1926, Serial No. 124,538, and inGreat BritainJuly 22, 1925.-

This invention relates to means for transferring heat from one fluid toanother, and more particularly' to heat interchangers used in connectionwith gases under considerable pressure such as the compressednitrogen-hydrogen gas mixture used for ammonia synthesis where the gasmixture,- after being heated by heat exchange with the het synthesizedgas mixture, is to be contacted, still lin the high'pressure condition,with abody of catalyst. f

'For efficient heat transfer between two fluids in an apparatus, it isnecessary that the liuids should travel heat-exchange relation with eachother over a lrelatively long path in relatively` thin layers orstrea1ns,and at a high velocity. lThe first requirement for travel overa relatively long patlrapparently necessitatesv long Or extendedapparatus while the requirement of high velocity particularlyiii-*conjunction with a long path of Vtravel tends to produce asubstantial pressure drop or pressure differential between the inlet andexit points u of the two fluid streams." Then large volumes of gas underconsiderable'pressure are handled, a substantial amount of power isconsumed in maintaining` the' requiredcirculation through the apparatus.rlhis isparticularly truevwhere, as in the synthesis of ammonia, thegases are subjected to a treatmentV at an established high pressure(which may be in'the hundredsof atmospheres) and Vare 'constantlyrecirculated, and where consequently a pressure drop requiresVthe'recirculating gases to be recompressed to 'the established pressurevalue.

The object of vthe' present invention is to provide an apparatus'whichwill give the required thin or divided fluid streams and length oftravel and which will be compact and economical to manufacture.

*A further object is to` provide a heat interehanger' through which thepressure drop or differential is reduced to a minimum.

A further object is to combine the improved interchanger unit witha unityfor catalytic reactions, so-that the' two operations of hea-tinterchange and catalysis can be conducted more efficiently and so thatthe outer wall of the apparatusmay be protected from the relatively hightemperature condition Vwhich I prevails in the catalyst body9 vTheaccompanying drawings illustrate o ne example of an embodiment oftheinvern tion. y The drawings will be described with particular i'eferenceto the synthesis of ammoniafrom its elements at an elevated temperatureand pressure; Fig. lis a sectional elevation of such apparatus and Fig.2 is a horizontal section on the lines 2-2 of Fig. 1.

Referring to Fig. 1, the numeral 1 designates a converter unit enclosingthe cylindrlcal catalyst compartment 2 formed byv a cylinder .2() andperforated end plates 3, 4. A heat interchanger unit 5 surrounds theconverter unit 1, it being of course understood that the whole apparatuslits into and is enclosed within a pressure resisting shell (not shown).The interchanger is divided into a plurality of concentric annularspaces 6, 7, 8, 9 andl 10 byV means of cylindrical baffle-likepartitions 11 and 12, openfor interrupted at one end, adjacentpartitions being` open at opposite ends as indicated at 13 and 18respectively. These partitions' or baflies are constructed of sheet ironwalls 21 between which asbestos 22 is tightly packed. rllheont-er andinner annular spaces are provided with gas openings-14 and 15. vThesespaces 6, 7, 8, 9 andl() therefore constitute a continuous gas passagefor gas entering the interchanger at lt and `leaving at 15 to enter" theconverter or vice versa.

A large number `of relatively small tubes G', '7,8' and9"traverse thecompartments 6, 7, 8 and 9 longitudinally and are arranged symmetricallytherein. Each set of parallel tubes is connected in series with theadjacent set or sets; for example, the ends of each pair of tubes 6"-7,8-9 etc.v adjacent the open end 13 of the bal'lles are connected byU'bends 16, and the opposite ends of each pair of tubes 7-8 adjacent theopen ends 13 of the battles are connected by means of annular concentricheaders 17 where'the gas, separated into a large nlnnber of streams bythe individual tubes, can mix before passing through the next set oftubes.

:The outer and inner headers are provided with gas openings 184 and19'so that, as in the case 'of the annular spaces, the sets of tubes andconnections constitute a continuous gas passage for gas entering at 19from the converter andvleaving at 18, or vice versa.

In the operation of my apparatus,

nitrogeii-liydrogen gas enters the circulatory system at 14, passesthrough the annular spacest, 7, 8, 9 and l() in series and enters theconverter unit, through the openings 15, and then passes into thecatalyst space 2,

y through the perforations in the supporting plate 4. Simultaneouslyhotcatalyzed gas passes from the converter unit into the tubes throughopenings 19, through the tubes of each setin parallel and through thesets of tubes in series and out of the circulatory system via opening18. During its passage through the annular spaces, the nitrogen*hydrogen gas is progressively heated by heat exchange from the hotsynthesized gasfiow-V plained, thence through the heat exchangertubes`9, 8, 7, and 6', and out at 18. From 18 the gases are conducted,as is customary in synthetic ammonia practice, through apparatus whereinammonia is removed from Vthe gases.. The residual gases of this ammoniaremoval treatment are then either passedto additional converters or, asdis- Yclosed Vin U. SfPatent No. 1,202,995 fof drawing.

October 31, 1916, issued to Haber et al., are

Vintroduced to the stream of fresh gasesof' Ythe same constitution whichis on its Way to the inlet 14 of the apparatus shown in the It has beenfound that an efficiency of' heat interchange of' about 80%-90% may beattained with my apparatus and thatthe pressure drop through theapparatus is very small, so that a relatively small amount of Work isnecessary to raise the pressure of the exit'gases once more to thesynthesis pres- ".sure. This pressure drop depends in part on the numberof tubes, decreasing with an increase in the number in' an annularspace. Oi course, there is a practical limit to the nun'iber of tubes,but as many as 300 can be satisfactorily disposed in an annular space 3feet vin mean diameter.

lIt is evident that the improved apparatus provides length oftravel anddivision of gas streamlwith great leconomy of kspace.

Another feature of the inventionis that p i the converter unit issurrounded by the heat 'interchanger unit so as to preserve uniform ytemperature conditions linthe Vcatalyst mass (i. e., no variable oruncontrolled heat losses) "Y and .to4 protect the pressure-resistingWall of the `apparatus (not shown vin the drawings) from the hightemperature conditions which prevail in the neighborhoood of thecatalyst.

VIt is preferred to 'pass the hot gases through vthe tubes; andV thecooler gases through theannular spaces, but the advantages of myinvention are also obtained although not inA full measure, with thereverse arrangement. f K

It will also be noted that the crosssectional area of each annular spaceor of each set of tubes can besmade the saine or can be varied bysuitable choice of the cross section of the vspaces and of the numberand size of the tubes. Y

It Will be further observed that the use of headers in Which the gasesfrom each set of tubes commingle is not an essential feature ot' theinvention. A single series of parallel continuous sinuoustubesextendingV up anddoivn the annular spaces from the inner space outwardsmayv be used. With this construction, of course, thenumber of tubes insuccessive annular spaces can not be varied, but Willibe the samethroughout.

Various modifications may be made with` out departing fromvthe natureVof my'invention as defined in the appended claims.

I claim: y

1. A heat interchanger for a circulatory pressure system comprising aplurality of Walls in telescoped relation to define compartments,connections joining said compartments so as to form a continuoustortuous gas passage, -means constituting a second gas passage, saidlmeans comprising a multiplicity of tubes extendinglongitudi- Vnallyofthe apparatus and positioned Within said first-mentioned tortuous gaspassage, so as to be in intimate thermal relation therewith and Agasinletand outlet means for the aforesaid passages. Y Y Y 2. Aheatinterchanger for a circulatory pressure syste-m comprising a pluralityof' Walls in telescoped relation to define comllt) par'tments,connections `betweensaid compartnients, forming with said compartments acontinuous -tortuous gas passage, means constituting a second gaspassage positioned With-in the first gas `passage,`so as to be inintimate thermal rela-tion therewith, saidY means beingV composed ofelements arranged to permit alength of flow of gas through said passageapproximating the shortest gas path through the first mentioned gaspassage countingfrom theV beginning to they end ofv the establishment ofthe heat,- interchange relation between the two said gas passages Vandgasinlet and outlet means for the aforesaid passages.1 Y A s `3. A heatinterchanger comprising a plurality of Walls in'rtelescoped relation todefine concentric annular compartments, connectionsjoining saidcompartments in series, so as'to constitute Ya continuous Vtortuousfluid passage, a plurality of sets of relatively small cross sectiontubes longitudinally positioned in the annular compartments, the tubesin any one compartment being arranged to aiford a parallel flou of'fluid through the tubes in said compartment, the sets of tubes beingconnected in series from compartment to compartment. so as toconstitute, all together, a second continuous tortuous fluid passage andgas inlet and outlet means for said compartments' and said secondpassage.

Ll. A heat interchanger comprising a plurality of Walls in telescopedrelation to detine concentric annular compartments connections joiningsaid eompartn'ients in seriesl so as to constitute a continuous tortuousfluid passage, a. plurality of circularly disposed sets of relativelysmall cross section tubes positioned longitudinally in the severalannular compartments, the tubes in any one compartment being arranged toallord a parallel flow of fluid through the tribes in said compartment,the sets of tribes being connected in series from compartment tocompartment, so as to constitute, all together, a second continuoustortuous fluid passage, a centralvcatalyst chamber positioned Within theaforesaid annular compartments, connections between one end of thecatalyst chamber and the inner set of tubes and between the other end ofthe catalystchamber and the inner annular compartment and gas inletl andoutlet means tor said compartments and said tribes.

5. A heat,inter-changer comprising a plurality of heat insulating` Wallsin telescoped relation to define concentric annular compartmentsconnections joining said compartments in series so as to constitute acon tinuous tortuous fluid passage, a plurality of sets of relativelysmall cross section tubos positioned longitudinally in the annularcompartments, the tubes in any one compartment belig arranged to ati'orda parallel flow of fluid through the tubes in said coinpartment, thesets of' tubes being connected in series from compartment to compartmentso as to constitute, all together, a second conh tinuous tortuous fluidpassage and inlet and outlet means for said compartments and said tubes.

6. A heat interchanger comprising a plurality of Walls in telescopedrelation to define concentric annular compartments connections joiningsaid compartments in series so as to constitute a continuous tortuousfluid passage, a plurality of sets of U tubes positioned longitu li allyin said compartments and disposed concentrically Within the saidinter-changer, the arms of each of' said tubes being located in adjacentcompartments, annular headers connecting the sets of U tubes in seriesso as to constitute a second continuous fluid passage traversing thesaid annular compartments and gas inlet and outlet means i'or said tuesand said compartments.

7. Ar heat interchangcr fora circulatory pressure system, comprisingplurality ot thermal insulating cylindrical battles defining annularspaces, connections between said spaces forming with said spaces acontinuons tortuous gas passage, a multiplicity of small cross-secti 1dtubes in each of said spaces, said tribes extending parallel to the axisof the apparatus and individually arranged to provide but a single passthrough each of the annular spaces, the tribes in each annular spacecommunicating with tubes of an adjacent annular Space throughconnections extending transverse of the cylindrical baliles so that thegas flows in parallel through all the tubes in each space.

8. A heat interchanger for a circulatory system, comprising a successiveseries of' annularly arranged nests et ttshapcd tubes, annular headersconnecting the adjacent legs of the lJ-shaped tribes of successivenests, thermal insulating cylindrical b s positioned in the annularspaces within the iiis of successive nests and between theheaderconnected legs ot' adjacent nests, said balllcs being alternatelyopen at their opposite ends whereby annular connected spaces are tormcdbetween successive bullies.

ln testimony whereof' I have hereunto set my hand.

FRANCIS H. BRAMWELL.

